Mass spectrometers are valuable tools for the in situ characterization of gaseous exo- and atmosp... more Mass spectrometers are valuable tools for the in situ characterization of gaseous exo- and atmospheres and have been operated at various bodies in space. Typical measurements derive the elemental composition, relative abundances, and isotopic ratios of the examined environment. To sample tenuous gas environments around comets, icy moons, and the exosphere of Mercury, efficient instrument designs with high sensitivity are mandatory while the contamination by the spacecraft and the sensor itself should be kept as low as possible. With the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), designed to characterize the coma of comet 67P/Churyumov-Gerasimenko, we were able to quantify the effects of spacecraft contamination on such measurements. By means of 3D computational modeling of a helium leak in the thruster pressurization tubing that was detected during the cruise phase we examine the physics involved leading to the measurements of contamination. 3 types of contamination can be distinguished: i) Compounds from the decomposition of the spacecraft material. ii) Contamination from thruster firing during maneuvers. iii) Adsorption and desorption of the sampled environment on and from the spacecraft. We show that even after more than ten years in space the effects of i) are still detectable by ROSINA and impose an important constraint on the lower limit of gas number densities one can examine by means of mass spectrometry. Effects from ii) act on much shorter time scales and can be avoided or minimized by proper mission planning and data analysis afterwards. iii) is the most difficult effect to quantify as it changes over time and finally carries the fingerprint of the sampled environment which makes prior calibration not possible.
When using radio techniques to observe meteors, one way of gaining insights into the physical phe... more When using radio techniques to observe meteors, one way of gaining insights into the physical phenomena that produce the meteor echoes is by analyzing the radio polarization of meteor trail echoes (Billam and Browne, 1956; Sidorov et al., 1965; Cannon, 1986). For example, the time variation of the polarization of meteor echoes can, in principle, provide information about electron densities in the meteor trail as shown by Poulter and Baggaley (1977) and by Jones and Jones (1990). Furthermore, the physical phenomena that lead to specific signature of some echoes in the time-frequency domains, such as the multiple-branch echoes, the so-called “epsilons” (Steyaert, 2012), are still not fully understood. The analysis of the polarization of such echoes can be used to increase our knowledge in this field.
METRO is the acronym for MEteor TRajectories and Origins. It is an interdisciplinary project with... more METRO is the acronym for MEteor TRajectories and Origins. It is an interdisciplinary project with a collaboration between several scientific institutes and also with radio amateurs. The METRO project focuses on radio meteor observations and what we can learned from them. For that purposes, the dataset from the BRAMS network are used. BRAMS (Belgian RAdio Meteor Stations) relies on forward scattering of radio waves emitted by a beacon in Dourbes off meteor ionization trails and received at 30 stations across Belgium. One of the main goal of METRO is to determine the trajectories of meteors in the sky. For some meteors, it is possible to retrieve meteor speed. Adding these two informations, we can trace back the orbit of the meteoroids. We present here the results of a method developed by Jones et al (1998) applied on the interferometric system based in Humain (Belgium). It consists in a 5 antennas configuration (two orthogonal sets of three aligned antennas with one central antenna c...
The ROSINA-DFMS mass spectrometer has been probing the coma of 67P since the spacecraft arrived a... more The ROSINA-DFMS mass spectrometer has been probing the coma of 67P since the spacecraft arrived at the comet in August 2014. The acquired data set covers a large range of viewing geometries for the ever changing conditions of 67P along its journey to pericenter. With the high temporal resolution of ROSINA-DFMS we are able to examine diurnal and seasonal changes of different species in the gaseous coma. Large scale heterogeneities in the coma have been reported since the very first measurements of the neutral inventory at 67P. Many of the minor species are seen to follow one of the major compounds, H 2 O, CO or CO 2 . In this paper we will present the latest results on H 2 O related species. We will discuss the possible trapping/building mechanisms responsible for these species and why it is different from other species such as CO, N 2 or CO 2 .
Context.The Rosetta spacecraft escorted Comet 67P/Churyumov-Gerasimenko for 2 yr along its journe... more Context.The Rosetta spacecraft escorted Comet 67P/Churyumov-Gerasimenko for 2 yr along its journey through the Solar System between 3.8 and 1.24 au. Thanks to the high resolution mass spectrometer on board Rosetta, the detailed ion composition within a coma has been accurately assessed in situ for the very first time.Aims.Previous cometary missions, such asGiotto, did not have the instrumental capabilities to identify the exact nature of the plasma in a coma because the mass resolution of the spectrometers onboard was too low to separate ion species with similar masses. In contrast, the Double Focusing Mass Spectrometer (DFMS), part of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis on board Rosetta (ROSINA), with its high mass resolution mode, outperformed all of them, revealing the diversity of cometary ions.Methods.We calibrated and analysed the set of spectra acquired by DFMS in ion mode from October 2014 to April 2016. In particular, we focused on the range from 1...
Noble gases in comet 67P/Churyumov-Gerasimenko indicate nonhomogenized protoplanetary disk materi... more Noble gases in comet 67P/Churyumov-Gerasimenko indicate nonhomogenized protoplanetary disk material at its location of formation.
Comets contributed to Earth's atmosphere Models of xenon's origin in Earth's atmosphe... more Comets contributed to Earth's atmosphere Models of xenon's origin in Earth's atmosphere require an additional, unknown source that has been a mystery for several decades. Marty et al. measured isotopic ratios of xenon released from comet 67P/Churyumov-Gerasimenko and found that they match the heretofore unknown source. The xenon appears to have been trapped in ice within the comet since before the solar system formed. Comets contributed about a quarter of the xenon on Earth, which constrains the amount of other materials (such as water) delivered to our planet by comets. Science , this issue p. 1069
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2017
The European Rosetta mission has been following comet 67P/Churyumov–Gerasimenko for 2 years, stud... more The European Rosetta mission has been following comet 67P/Churyumov–Gerasimenko for 2 years, studying the nucleus and coma in great detail. For most of these 2 years the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has analysed the volatile part of the coma. With its high mass resolution and sensitivity it was able to not only detect deuterated water HDO, but also doubly deuterated water, D2O and deuterated hydrogen sulfide HDS. The ratios for [HDO]/[H2O], [D2O]/[HDO] and [HDS]/[H2S] derived from our measurements are (1.05 ± 0.14) × 10−3, (1.80 ± 0.9) × 10−2and (1.2 ± 0.3) × 10−3, respectively. These results yield a very high ratio of 17 for [D2O]/[HDO] relative to [HDO]/[H2O]. Statistically one would expect just 1/4. Such a high value can be explained by cometary water coming unprocessed from the presolar cloud, where water is formed on grains, leading to high deuterium fractionation. The high [HDS]/[H2S] ratio is compatible with upper limits determined in low-mass ...
Context.The ESA Rosetta mission has been investigating the environment of comet 67P/Churyumov-Ger... more Context.The ESA Rosetta mission has been investigating the environment of comet 67P/Churyumov-Gerasimenko (67P) since August 2014. Among the experiments on board the spacecraft, the ROSINA experiment (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) includes two mass spectrometers to analyse the composition of neutrals and ions and a COmet Pressure Sensor (COPS) to monitor the density and velocity of neutrals in the coma.Aims.We study heterogeneities in the coma during three periods starting in October 2014 (summer in the northern hemisphere) and ending in February 2016 (end of winter in the northern hemisphere). We provide a detailed description of the main volatiles dynamics (H2O, CO2, CO) and their abundance ratios.Methods.We analysed and compared the data of the Reflectron-type Time-Of-Flight (RTOF) mass spectrometer with data from both the Double Focusing Mass Spectrometer (DFMS) and COPS during the comet escort phase. This comparison has demonstrated that the observa...
Mass spectrometers are valuable tools for the in situ characterization of gaseous exo- and atmosp... more Mass spectrometers are valuable tools for the in situ characterization of gaseous exo- and atmospheres and have been operated at various bodies in space. Typical measurements derive the elemental composition, relative abundances, and isotopic ratios of the examined environment. To sample tenuous gas environments around comets, icy moons, and the exosphere of Mercury, efficient instrument designs with high sensitivity are mandatory while the contamination by the spacecraft and the sensor itself should be kept as low as possible. With the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), designed to characterize the coma of comet 67P/Churyumov-Gerasimenko, we were able to quantify the effects of spacecraft contamination on such measurements. By means of 3D computational modeling of a helium leak in the thruster pressurization tubing that was detected during the cruise phase we examine the physics involved leading to the measurements of contamination. 3 types of contamination can be distinguished: i) Compounds from the decomposition of the spacecraft material. ii) Contamination from thruster firing during maneuvers. iii) Adsorption and desorption of the sampled environment on and from the spacecraft. We show that even after more than ten years in space the effects of i) are still detectable by ROSINA and impose an important constraint on the lower limit of gas number densities one can examine by means of mass spectrometry. Effects from ii) act on much shorter time scales and can be avoided or minimized by proper mission planning and data analysis afterwards. iii) is the most difficult effect to quantify as it changes over time and finally carries the fingerprint of the sampled environment which makes prior calibration not possible.
When using radio techniques to observe meteors, one way of gaining insights into the physical phe... more When using radio techniques to observe meteors, one way of gaining insights into the physical phenomena that produce the meteor echoes is by analyzing the radio polarization of meteor trail echoes (Billam and Browne, 1956; Sidorov et al., 1965; Cannon, 1986). For example, the time variation of the polarization of meteor echoes can, in principle, provide information about electron densities in the meteor trail as shown by Poulter and Baggaley (1977) and by Jones and Jones (1990). Furthermore, the physical phenomena that lead to specific signature of some echoes in the time-frequency domains, such as the multiple-branch echoes, the so-called “epsilons” (Steyaert, 2012), are still not fully understood. The analysis of the polarization of such echoes can be used to increase our knowledge in this field.
METRO is the acronym for MEteor TRajectories and Origins. It is an interdisciplinary project with... more METRO is the acronym for MEteor TRajectories and Origins. It is an interdisciplinary project with a collaboration between several scientific institutes and also with radio amateurs. The METRO project focuses on radio meteor observations and what we can learned from them. For that purposes, the dataset from the BRAMS network are used. BRAMS (Belgian RAdio Meteor Stations) relies on forward scattering of radio waves emitted by a beacon in Dourbes off meteor ionization trails and received at 30 stations across Belgium. One of the main goal of METRO is to determine the trajectories of meteors in the sky. For some meteors, it is possible to retrieve meteor speed. Adding these two informations, we can trace back the orbit of the meteoroids. We present here the results of a method developed by Jones et al (1998) applied on the interferometric system based in Humain (Belgium). It consists in a 5 antennas configuration (two orthogonal sets of three aligned antennas with one central antenna c...
The ROSINA-DFMS mass spectrometer has been probing the coma of 67P since the spacecraft arrived a... more The ROSINA-DFMS mass spectrometer has been probing the coma of 67P since the spacecraft arrived at the comet in August 2014. The acquired data set covers a large range of viewing geometries for the ever changing conditions of 67P along its journey to pericenter. With the high temporal resolution of ROSINA-DFMS we are able to examine diurnal and seasonal changes of different species in the gaseous coma. Large scale heterogeneities in the coma have been reported since the very first measurements of the neutral inventory at 67P. Many of the minor species are seen to follow one of the major compounds, H 2 O, CO or CO 2 . In this paper we will present the latest results on H 2 O related species. We will discuss the possible trapping/building mechanisms responsible for these species and why it is different from other species such as CO, N 2 or CO 2 .
Context.The Rosetta spacecraft escorted Comet 67P/Churyumov-Gerasimenko for 2 yr along its journe... more Context.The Rosetta spacecraft escorted Comet 67P/Churyumov-Gerasimenko for 2 yr along its journey through the Solar System between 3.8 and 1.24 au. Thanks to the high resolution mass spectrometer on board Rosetta, the detailed ion composition within a coma has been accurately assessed in situ for the very first time.Aims.Previous cometary missions, such asGiotto, did not have the instrumental capabilities to identify the exact nature of the plasma in a coma because the mass resolution of the spectrometers onboard was too low to separate ion species with similar masses. In contrast, the Double Focusing Mass Spectrometer (DFMS), part of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis on board Rosetta (ROSINA), with its high mass resolution mode, outperformed all of them, revealing the diversity of cometary ions.Methods.We calibrated and analysed the set of spectra acquired by DFMS in ion mode from October 2014 to April 2016. In particular, we focused on the range from 1...
Noble gases in comet 67P/Churyumov-Gerasimenko indicate nonhomogenized protoplanetary disk materi... more Noble gases in comet 67P/Churyumov-Gerasimenko indicate nonhomogenized protoplanetary disk material at its location of formation.
Comets contributed to Earth's atmosphere Models of xenon's origin in Earth's atmosphe... more Comets contributed to Earth's atmosphere Models of xenon's origin in Earth's atmosphere require an additional, unknown source that has been a mystery for several decades. Marty et al. measured isotopic ratios of xenon released from comet 67P/Churyumov-Gerasimenko and found that they match the heretofore unknown source. The xenon appears to have been trapped in ice within the comet since before the solar system formed. Comets contributed about a quarter of the xenon on Earth, which constrains the amount of other materials (such as water) delivered to our planet by comets. Science , this issue p. 1069
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2017
The European Rosetta mission has been following comet 67P/Churyumov–Gerasimenko for 2 years, stud... more The European Rosetta mission has been following comet 67P/Churyumov–Gerasimenko for 2 years, studying the nucleus and coma in great detail. For most of these 2 years the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has analysed the volatile part of the coma. With its high mass resolution and sensitivity it was able to not only detect deuterated water HDO, but also doubly deuterated water, D2O and deuterated hydrogen sulfide HDS. The ratios for [HDO]/[H2O], [D2O]/[HDO] and [HDS]/[H2S] derived from our measurements are (1.05 ± 0.14) × 10−3, (1.80 ± 0.9) × 10−2and (1.2 ± 0.3) × 10−3, respectively. These results yield a very high ratio of 17 for [D2O]/[HDO] relative to [HDO]/[H2O]. Statistically one would expect just 1/4. Such a high value can be explained by cometary water coming unprocessed from the presolar cloud, where water is formed on grains, leading to high deuterium fractionation. The high [HDS]/[H2S] ratio is compatible with upper limits determined in low-mass ...
Context.The ESA Rosetta mission has been investigating the environment of comet 67P/Churyumov-Ger... more Context.The ESA Rosetta mission has been investigating the environment of comet 67P/Churyumov-Gerasimenko (67P) since August 2014. Among the experiments on board the spacecraft, the ROSINA experiment (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) includes two mass spectrometers to analyse the composition of neutrals and ions and a COmet Pressure Sensor (COPS) to monitor the density and velocity of neutrals in the coma.Aims.We study heterogeneities in the coma during three periods starting in October 2014 (summer in the northern hemisphere) and ending in February 2016 (end of winter in the northern hemisphere). We provide a detailed description of the main volatiles dynamics (H2O, CO2, CO) and their abundance ratios.Methods.We analysed and compared the data of the Reflectron-type Time-Of-Flight (RTOF) mass spectrometer with data from both the Double Focusing Mass Spectrometer (DFMS) and COPS during the comet escort phase. This comparison has demonstrated that the observa...
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